Confocal-Assisted Fluorescence Resection of Low-Grade Gliomas

Abstract

INTRODUCTION: Low-grade gliomas (LGG) are the most common intra-axial brain tumors. Intraoperatively it's not possible to distinguish optically between the tumor and the normal tissue. Furthermore, it can not be detected with fluorescent agents like 5-aminolevulinacid (5-ALA). Those reasons often lead to inaccurate resection of the tumor. Confocal laser endomicroscopy (CLE) is a cellular imaging modality used for optical biopsies. The aim of this study was to use intraoperative CLE to differentiate tumor from normal tissue and to define borders during resection of LGG on a cellular level. METHODS: We investigated the use of intraoperative CLE on 6 patients with LGG. We used a confocal system that is able to detect fluorescence on the infrared spectrum and we applied indocyanine green as a detecting fluorescent agent. We analyzed the accuracy of the intraoperative cellular CLE optical biopsies in comparison with the hematoxylin and eosin stains of the biopsies taken from the tumor and normal tissue borders area. RESULTS: With CLE we were able intraoperatively to diagnose the tumor entity, normal brain structures, and vascularization modalities and to control the resection zone on a cellular level. Furthermore, CLE pictures showed exactly the cellular borders between tumor and normal tissue. The correlation of the CLE pictures with the H & E staining was 100%. CONCLUSION: CLE, on one hand, allows intraoperative detection and differentiation of single tumor cells, while, on the other hand, it allows defining borders between tumor and normal tissue on a cellular level, dramatically improving the accuracy of surgical resection of LGG. The application and implementation of CLE-assisted surgery increases not only the options for real-tumor identification but also the therapeutic options by extending the resection borders of LGGon a cellular level and, more importantly, by protecting the functionality of normal tissue on the adjacent areas of the human brain.